Cutter knives and methods of making the same



United States Patent Inventor Charles Wesley Murray Franklin Park, Pennsylvania 756,021 Aug. 28, 1968 Nov. 24, 1970 Appl. No. Filed Patented Assignee Heppenstall Company a corporation of Pennsylvania CUTTER KNIVES AND METHODS OF MAKING THE SAME 7 Claims, 2 Drawing Figs.

US. Cl

Int. Cl

Field of Search 76/101; 83/698 B23171 35/00 83/676, 698;76/101, 101A; 29/47l.1

References Cited UNITED STATES PATENTS 3/1963 W. MacPherson 83/676 FOREIGN PATENTS 8/1911 Austria 76/101A 6/1961 Great Britain. 83/698 8/1932 Switzerland... 76/101A 6/1944 Switzerland 76/101A Primary ExaminerAndrew R. Juhasz Assistant Examiner-Leon Gilden AttorneyBue11,Blenko & Ziesenheim ABSTRACT: A composite cutter is provided having an outer annular carbide cutter ring, and a plurality of slightly spaced apart hub segments metallurgically bonded to said cutter ring within said annulus and forming a shaft receiving opening. The hub segments are joined radially by a low temperature bonding compound such as epoxy.

Patented Nov. 24, 1970 3,541,910

INVENTOR Charles Wesley Murray 2 wgww CUTTER KNIVES AND METHODS OF MAKING THE SAME keyway or spline through which the knife is driven. Many sive strength to hold the, segments in alignment and positioned apart as an integral unit.

1n the foregoing general description, 1 have set out certain objects, purposes and advantages of my invention. Other ob- 5 jects, purposes and advantages of my invention will be apmethods'of assembling a carbide cutter ring on a steel hub have been tried but without complete success. In order to obtain the necessary strength of bond between the hub and carbide cutter, it is necessary to metallurgically bond the cutter and hub by brazing or soldering. Unfortunately, the coefficients of expansion of the steel hub and the carbide ring are so different that the carbide ring and the braze joint areplaced under such stress on cooling of the assembly that one 'or the other or both break. This may happen immediately on cooling or shortly after beginning the use of the knife, both of which are, of course, fatal to use of the knife. Many efforts to overcome this problem have been attempted; for example, the carbide has been attached with resinous adhesives such as epoxies, but the life has been unsatisfactorily' short because the resin will not stand up under the high temperature shear stresses which occur in use. Mechanical fasteners have also been attempted, but these too are not satisfactory, both because of the considerable expense involved and the difficulty of holding the carbide and hub in fixed relative positions Other means have been proposed as for example in MacPherson US. Pat. No. 3,081,661 in which an annular carbide cutter is attached to a plurality of spaced semiannular segments by brazing and the segments are then attached to a solid hub by means of mechanical fasteners. This structure solves the problem ofdifferential contraction of steel and carbide at their brazed joint but introduces considerable expense in the mechanical connection to thehub and does not entirely solve the problem of holding the hub and outer ring in fixed position.

l have discovered an annular cutter knife structure and method of assemblywhich solves these problems ofthe prior art and provides an inexpensive but positive connection between the steel hub and carbide cutter ring.

Preferably, I provide a steel hub assembly. in a plurality of semiannular segments, each segment is metallurgically bonded to an annular carbide ring in the interior of the annulus with a slight spacing between each segment and the assembled adjacent'segments are thenjointed together by a low temperature bonding material such as epoxy resin. The hub is preferably formed in three 120 segments by cutting a preformed hub by sawing with a thin blade such as for example a one-sixteenth inch saw cut. The hub segments are preferably brazed or silver soldered into the annulus of the carbide cutter ring with a uniform spacing between them. This eliminates the braze strain'problem-After brazing or soldering and cooling, the hub segments are cemented together with epoxy resin or the like having sufficient bonding and compresparent from a consideration of the following description and the accompanying drawings in which:

FIG. 1 is a side elevation of a cutter knife according to my invention; and

FIG. 2 is a section on the line 11-11 of P10. 1.

Referring to the drawings, 1 have illustrated a cutter knife accol'ding to my'invention madeup of an outer annular carbide cutter ring attached to the three steel hub segments 11, -12-and 13 formed by cuttin l20 segments from a preformed solid hub using a saw ma mg a one-sixteenth inch cut. The cutter ringl0 is attached to segments 11, 12 and 13 by braze metal'l4. The gap 15 between the segments 11, 12

and 13 is filled with-epoxy resin 16 to make an integral assembly. The gap 15 may be left open in some cases and the cutter knife used without filling the gap, however, for most high strength uses the gap should be filled with bonding material to impart rigidity and compressive strength to the segments.

While 1 have illustrated and described certain preferred practices and embodiments of my invention in the foregoing specification, it will be understood that this invention may be otherwise embodied within the scope of the following claims.

cutter and hub segments are bonded by brazing.

1 claim: 1 g

' 1. A composite annular cutter knife comprising an outer carbide annular cutter ring, a plurality of hub segments metallurgically bonded to said cutter ring within the annulus, said hub segments being spaced slightly apart and extending radially inwardly to form a shaft receiving opening and a low temperature bonding material between the hub segments bonding the same into a unitary structure.

2. A cutter knife as claimed in claim 1 wherein the hub segments are substantially 120 segments.

3. A cutter knife as claimed in claim 1 wherein the low temperature bonding material is epoxy resin.

4. A cutter knife as claimed in claim 3 wherein the carbide 5. A cutter knife as claimed in claim 3 wherein the carbide cutter and hub segments are bonded by soldering.

6. A method of making a composite cutter knife having an outer carbide cutter ring and a steel hub comprising the steps a. forming anannular carbide cutter ring; b. forming a plurality of semiannular hub segments of steel;

c. r'netallurgically bonding each of said hub segments within the annulus of the carbide cutter with each segment slightly spaced apart .and extending radially inwardly forming a drive shaft receiving portion; and 

